Typically used within web applications that require some programmatic initialization
of the application context. For example, registering property sources or activating
profiles against the context's environment. See ContextLoader and FrameworkServlet support
for declaring a "contextInitializerClasses" context-param and init-param, respectively.

ApplicationContextInitializer processors are encouraged to detect
whether Spring's Ordered interface has been
implemented or if the @Order
annotation is present and to sort instances accordingly if so prior to invocation.